When I torque down the inner assembly of the oil pump, it gets so tight that it binds the gears (between the plate and the back of the housing) to the point where they almost cant be turned by hand:

- is there a gasket that goes here to create the correct clearances? according to this thread (linked below) there is, but a search for that product number returns nothing and I don't see one in the online catalog.

Thursty, There is a gasket that belongs there which is supplied in the complete gasket set. Ken, in parts may be able to send you one, but if not, one can be made from .010" fiber gasket material available at most auto parts stores. The part # in the "Universal A4 Parts Manual" is 261009.
Tom

FWIW. When I rebuilt my A-4 I decided to disassemble and clean the oil pump. Before disassemble it spun freely. After reassembling it was hard to turn. I spoke to Don about this and he suggested running the gear back and forth on a table to loosen things up. This helped some. I continued with the rebuild and have had no issues with the pump and have put a bunch of hours on it.
Dan S/V Marian Claire

Don't feel you're cheating or compromising your engine by making your own gaskets. All the gasket does is hold the sealing compound in place so the irregularities in the machined surfaces get filled. The 'garden variety' fiber gaskets are easiest - just try to match the thickness of the original gasket. Printer paper, paper bags, and card stock are all good candidates.
In making gaskets for the cover of the water pump, I don't even cut out the center - the impeller will do that job.
Some 'special' gaskets I will buy: head gaskets and exhaust manifold come to mind due to the high temperatures.
About sealants: for oil systems I use the brown stuff - Aviation Permatex? You need alcohol to get it off your fingers. For water systems, I use the blue silicone. I think they're both from Permatex, so using the Permatex name really doesn't tell much. Come to think of it, I suspect the Loctite stuff for threads also comes from Permatex. All good products - buy their stock? Kinda like 3M - good products.

Al is correct about making your own gaskets. I have taken that hobby one step farther and created my own gasket making kit , which is comprised of several different thicknesses and types of actual gasket material, carbon paper, a hole punch set, Exacto knives and computer scanned prints of most of the gaskets that I commonly use. While scanning the originals, I measure their thickness and note that on the prints. The main reason for going to all of this trouble is not to save money but rather to be able to create "parts" upon demand.
Tom